<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
	</body>
	<script type="text/javascript">
		function test(arr,fn){
			arr =arr||Array.prototype;
			fn =fn||Function.prototype;
			/*arr=arr||[];
			fn = fn||function(){};*/
			return arr.map(fn);
		}
		console.log(test());
		
	</script>
</html>
